Theoretical study of thermal response of bimaterial microcantilevers with different coating materials

Abstract

Bilayer microcantilevers are a versatile tool in thermal and bio-sensing with responses relying on the mismatch between the two constituting materials. The cantilever response, such as a deflection and resonance frequency shift, could be involved when the cantilever is in contact with an arbitrary heat source in the ambient environment. In this study, thermally induced deflection will be theoretically examined assuming a heat source located at various positions on the cantilever. The combined contributions of heat absorption, thermal conductivity, and material rigidity on the final deflection will be revealed. Selecting an optimal position leads to 1.5 times enhancement of the cantilever deflection in comparison to thermal excitation at the cantilever end in conventional experiments, which implies a significant increase in thermal sensitivity. Furthermore, responses of cantilevers with different coating materials (Au, Al, Cu, or Ni) have been examined and show a dominant sensitivity of Al- and Ni- over Cu- and Au-coated cantilevers. These results could help to explain recent experimental results and to choose an optimal thermal excitation of microcantilevers in sensing.